Portable medium

Details Portable medium Portable medium

1988-03-30

1989-03-21

Pitts, Harold I.

Registers

Systems controlled by data bearing records

Credit or identification card systems

235379, G06K 510

Patent

active

048145912

ABSTRACT:
An IC card, i.e., a portable medium, contains a data memory and a CPU functioning as a control element. The IC card has a keyboard and a built-in battery. It also includes a clock controller, a first clock generator always generating a low-frequency clock signal, and a second clock generator having a oscillator, for generating a high-frequency clock signal. When the IC card is used in an off-line mode, that is, when it is used by itself, it is driven by the battery. The CPU performs various operations in accordance with the signals input by operating the keyboard. When the power-on key of the keyboard is pushed in the off-line mode, the clock controller supplies the low-frequency clock signal to the CPU, and simultaneously causes the second clock generator to generate the high-frequency clock signal. When the next signal is input from the keyboard, the clock controller supplies the high-frequency clock signal, instead of the low-frequency clock signal, to the CPU.

REFERENCES:
patent: 4529780 (1985-07-01), Chaum
patent: 4697072 (1987-09-01), Kawana

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